KR960002894B1 - Dry developer - Google Patents

Abstract

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Description

Dry Developer (DRY DEVELOPER)

The present invention relates to a dry developer used for developing electrostatic latent images in electrophotography or in an electrostatic recording process.

The dry developer can be classified into a single component developer using only a toner formed by dispersing a complexing agent in a binder resin, and a two component developer comprising a mixture of the toner and a carrier. The electrostatic latent image developed on the photoconductor and the like is developed by the developer and the toner image formed is transferred to the transfer paper, and then the toner remaining on the photoconductor is washed. Therefore, the dry developer should be one that satisfies various conditions in the photocopying step, in particular in the developing step or the washing step. In particular, toner without aggregation of each particle during development is used for development, and for this purpose, the toner must have sufficient fluidity, and its fluidity or electrical properties may change over time or with changes in environmental conditions (eg, temperature and humidity). Should not be changed by In addition, the two-component developer should not cause so-called toner film formation, i.e., toner adheres to the carrier surface.

In addition, the toner should have a cleaning property such that residual toner on the surface of the photoconductor can be easily removed during cleaning, and must not damage the photoconductor surface when a cleaning member such as a blade or a web is used for cleaning the residual toner.

In order to meet these requirements, two-component developers prepared by adding various single-component developers or inorganic fine powders such as silica, organic fine powders such as fatty acids or derivatives thereof, or metal salts to the toner are fluid, durable or washable. Etc. have been suggested to be improved.

However, conventionally proposed additives for toner, i.e., inorganic oxides such as silica, titania, alumina, etc., remarkably improve the fluidity of the developer, whereas the inorganic oxides themselves are quite hard, thus damaging the photosensitive surface and consequently the parts thereof. Toner adheres to the

In addition, in the case of the organic belt photosensitive member for a high speed copying machine, a cleaning device using a rubber knife or a brush is employed, but the cleaning performance is remarkably deteriorated due to the bending and bending of the organic belt photosensitive member as compared with the conventional drum photosensitive cleaning apparatus. Paper dust, etc., enters between the photoreceptor and the blade, resulting in poor cleaning.

In addition, in recent years, the demand for low voltage and high developability is increasing, and therefore, a low specific gravity low dispersion type carrier having an essential component of resin and magnetic powder has been used. However, such carriers tend to adhere to the surface of the photoconductor and thus damage the surface of the photoconductor upon washing.

Accordingly, an object of the present invention is to solve the above problems and to provide a dry developer which is good in fluidity and washability, excellent in stability and durability to the environment, and can prevent toner film formation on the surface of the photoconductor or carrier. have.

This object is achieved by the present invention as follows.

That is, the present invention is a dry developer for electrophotographic processing of cleaning a toner by pressing a rubber knife, a brush, etc. on the surface of an organic belt photoconductor, and comprising a toner, a dispersion carrier containing a resin and magnetic powder, And a polyethylene having a molecular weight of 10,000 or less and a density of 0.95 or more and an average volume diameter of 15 μm or less is blended with the toner from the outside or directly mixed with a developer.

Next, the present invention will be described in detail.

As for the polyethylene used in the present invention, the molecular weight thereof is preferably 900 or more and its density is 0.99 or less.

In the present invention, the content of the polystyrene contained in the dry developer is 0.01 to 10% by weight, more preferably 0.2 to 2% by weight based on the total weight of the toner. When the content is 0.01% by weight or less, the washability tends to be lowered. When the content is more than 10% by weight, the developability tends to be lowered due to the triboelectric charge of the toner.

In externally adding polyethylene to the toner, the polyethylene may be mechanically mixed with each other, and the polyethylene may be attached to the surface of the toner in the form of almost a dispersion. In addition, the polyethylene fine powder may not be applied to the entire surface of the toner particles, or may be applied as a partial aggregate of polyethylene fine powder, but it is preferable to apply the toner with a single layer of fine powder.

The dry developer of the present invention is used as a two-component developer comprising the toner and the dispersion carrier.

In forming the always-two-component developer, the toner to which the polyethylene fine powder is externally added may be mixed with the carrier, or the toner, the carrier and the polyethylene fine powder may be mixed at the same time. In this case, a double cylinder mixer, a Henschel mixer, or the like can be used.

In addition, the toner is mainly composed of a binder resin and a colorant.

-메틸렌 지방족 모노카르복시산 에스테르류 ; 비닐메틸에테르, 비니에틸에테르, 비닐부틸에테르등의 비닐에테르류 ; 비닐메틸케톤, 비닐헥실케톤, 비닐이소프로필페닐케톤등의 비닐케톤류등.Examples of the binder resin include homopolymers or copolymers of the following compounds: styrenes such as styrene and chlorostyrene; Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; Monoolefins such as ethylene, propylene, butylene and isobutylene; Methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, etc.

-Methylene aliphatic monocarboxylic acid esters; Vinyl ethers such as vinyl methyl ether, bean ethyl ether, and vinyl butyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropyl phenyl ketone.

Representative binder resins include polystyrene, styrene-alkyl methacrylate copolymers, styrene-alkyl methacrylate copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, polyethylene and polypropylene Etc.

In addition, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, wax and the like can also be used as the binder resin.

Representative examples of the colorants used in the present invention include carbon black, anilan blue, chacoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate. There are lamps, black and rose bangle.

Since the polyethylene coating can significantly lower the coefficient of friction, adding TiO ₂ , SiO ₂ , Al ₂ O _2, etc. to the toner externally prevents the inorganic particles from adhering to the photoconductor, thereby preventing damage.

In addition, the toner used in the present invention may use a magnetic toner or a capsule toner containing a magnetic material.

The average particle diameter of the toner in the present invention is about 30 µm or less, preferably 3 to 20 µm.

In addition, the carrier is a dispersed carrier having a resin and a magnetic powder as main components.

As the resin, the above-described polymers or copolymers can be used as the binder resin for the toner.

In addition, the magnetic powder may be used as fine particles of a ferromagnetic material that is commercially available for such a carrier. Specific examples thereof include iron trioxide, iron γ-sesquioxide, various ferrites, chromium oxide and various fine metal powders.

The carrier may further contain a static control agent as necessary.

The carrier in the present invention can be prepared by kneading, pulverizing and classifying the above components or by using a solvent to form a liquid of the above components or by heating and spray drying the liquid.

The average particle diameter of the carrier used in the present invention is about 20 to 400 mu m, preferably 30 to 200 mu m.

In the present invention, the carrier to toner content ratio in the dry developer is usually 90:10 to 98: 2 (weight ratio).

The dry developer of the present invention comprises a toner mainly composed of a binder resin and a colorant, and a dispersion carrier mainly composed of a resin and a magnetic powder. In the present invention, polyethylene fine powder having a molecular weight of 10,00 or less, a density of 0.95 or more, and an average volume diameter of 15 μm or less may be externally added to the toner first, and then the toner may be mixed with a carrier, or the polyethylene fine powder is toner It may be added at the time of mixing with the carrier.

The dry developer of the present invention is applied to a high-speed development method for developing a latent image moving at high speed, that is, an electrophotographic method for cleaning an organic belt photosensitive member using a rubber blade, a brush, or the like. In this case, since the blend of polyethylene fine powder is used, a lubrication effect is obtained, and the lubrication layer is formed in the photoreceptor surface, and it exhibits the effect which a void area or a flow does not generate | occur | produce on the formed. In order to form this lubricating layer or film, the molecular weight of the polyethylene used must be 10,000 or less, and the density is 0.95 or more and the average volume diameter (d ₅₀ ) is 15 µm in order to obtain a lubricating effect without adhesion fusion of polyethylene fine powder on the photoreceptor. Hereinafter, polyethylene fine powder having a thickness of preferably 10 μm or less should be used. The preferred average volume diameter should be as small as possible, but should be at least about 3 μm for manufacturing purposes.

Next, Examples and Comparative Examples of the present invention will be described, but the present invention is not limited to these Examples. In addition, in the following Examples and Comparative Examples, "parts" are parts by weight.

Example 1

Styrene-butyl acrylate copolymer (80/20 parts by weight)

Ten copies of carbon black (Regal 330 (brand name) car boat company)

5 parts of low molecular weight polypropylene (Viscol 660P, brand name, Sanyo Chemical Co., Ltd.)

1 part of electrostatic control agent (Bontron N-03, brand name, product made by Orient Chemical Industries, Ltd.)

The components were melted, kneaded and cooled in a banbari mixer, and then the solidified mixture was pulverized with a jet mill, and then the pulverized particles were classified with a classifier to obtain a toner having an average volume diameter (d ₅₀ ) of 11 mu m.

Next, 1 part of fine silica particles having an average volume diameter of 0.1 mu m, 0.5 parts of polyethylene having a mean volume diameter of 8 mu m, a density of 0.97, and a molecular weight of 9000 (Ceridust 3620, trade name, manufactured by Hoechst A. G) were prepared. The toner was obtained by dispersion mixing using a blender.

On the other hand, 100 parts of styrene-methyl methacrylate (80/20 weight ratio) copolymer, 200 parts of magnetide (EPT-1000, Tody Industries Co., Ltd.), 5 parts of perivinylidene fluoride (KYNAR) by Penn Walt) Melt kneading was carried out in a kneader, and the kneaded mixture was then ground by a turbo mill and classified to obtain a tin with an average volume diameter d ₅₀ of 50 µm.

The toner and the tin were mixed with each other in a ratio of 5:95 weight ratio to obtain a two-component developer.

Example 2

The same ingredients as in Example 1 were kneaded, pulverized and classified to give a toner having an average volume diameter of 11 mu m. Next, 100 parts of this toner, 1 part of fine titanium oxide particles having an average volume diameter of 0.1 mu m, and 0.5 parts of polyethylene prepared by freeze-grinding having an average volume diameter of 6 mu m, a density of 0.97 and a molecular weight of 5,000 (200P, a brand name, the Mitsui Sekiyu Chemical Co., Ltd. product) was disperse | distributed and mixed by the blender. The obtained toner was mixed with a carrier in the same manner as in Example 1 to obtain a two-component developer.

Example 3

The same ingredients as in Example 1 were kneaded, pulverized and classified to give a toner having an average volume diameter of 11 mu m. 100 parts of this toner, 1 part of fine titanium oxide particles having an average volume diameter of 0.1 mu m, and 0.5 parts of polyethylene having an average volume diameter of 6 mu m, a density of 0.96 and a molecular weight of 6,000 (Acumist B6, trade name, manufactured by Allid Chemical Co., Ltd.) By dispersing and mixing. The obtained turner was mixed with a carrier in the same manner as in Example 1 to obtain a two-component developer.

Example 4

The same ingredients as in Example 1 were kneaded, pulverized and classified to give a toner having an average volume diameter of 11 mu m. Next, 100 parts of etonner, 1 part of fine titanium oxide particles having an average volume diameter of 0.1 μm, and 0.5 parts of polyethylene having an average volume diameter of 0.5 μm, a density of 0.95 and a molecular weight of 2,300 (Acumist C5, trade name, manufactured by Allid Chemical Co., Ltd.) Was dispersed and mixed by a blender. The obtained toner was mixed with a carrier in the same manner as in Example 1 to obtain a two-component developer.

Example 5

The same ingredients as in Example 1 were kneaded, pulverized and classified to give a toner having an average volume diameter of 11 mu m. Next, 100 parts of the toner, 1 part of fine titanium oxide particles having an average volume diameter of 0.1 µm, and 0.5 parts of polyethylene produced by freeze-pulverization having an average volume diameter of 15 µm, a density of 0.97 and a molecular weight of 5,000 (200 P, trade name, Mitsui Sekiyu Kagaku Co., Ltd.) was dispersed and mixed with a blender. The obtained toner was mixed with a carrier in the same manner as in Example 1 to obtain a two-component developer.

Example 6

The same ingredients as in Example 1 were kneaded, pulverized and classified to give a toner having an average volume diameter of 11 mu m. Next, 100 parts of the toner, 1 part of fine titanium oxide particles having an average volume diameter of 0.1 μm, and 0.5 parts of polyethylene produced by freeze grinding having an average volume diameter of 12 μm, a density of 0.97 and a molecular weight of 10,000 (600P, trade name, Mitsui Sekiyu Kagaku Co., Ltd.) was dispersed and mixed with a blender. The obtained toner was mixed with a carrier in the same manner as in Example 1 to obtain a two-component developer.

Comparative Example 1

Example 1 was performed similarly except not using a polyethylene fine powder, and the two-component developer was obtained.

Comparative Example 2

A two-component developer was obtained in the same manner as in Example 1 except that 0.5 parts of calcium stearate (average volume diameter 1 µm) having a lubricating effect was used instead of the polyethylene fine powder.

Comparative Example 3

A two-component developer was obtained in the same manner as in Example 2 except that polyethylene micropowder having an average volume diameter of 20 μm was used.

[Comparative Example 4]

The same procedure as in Example 1 was carried out except that 0.5 parts of a fine powder having an average volume diameter of 8 µm was used by freezing and pulverizing polyethylene having a density of 0.92 and a molecular weight of 5,000 (220P, trade name, manufactured by Mitsui Oil Industries, Ltd.). To obtain a two-component developer.

[Comparative Example 5]

The component developer was obtained in the same manner as in Example 1 except that 0.5 part of a polyethylene having a density of 0.96 and a molecular weight of 40,000 was freeze-pulverized to obtain a fine powder having an average volume diameter of 9 μm instead of the polyethylene fine powder.

[Copy Test]

Using the respective dry developers obtained in Examples 1 to 3 and Comparative Examples 1 to 5, a continuous copy test was conducted with an electrophotographic copying machine (FX5075, trade name Fuji Xerox Co., Ltd.), and the results are shown in the following table. This continuous copy test was repeated at 10 second intervals for 999 copies.

[table]

Note: 1) The density was measured according to the method of JIS K6760.

2) The average volume diameter D ₅₀ (Vol) was measured using a culter counter (type TA-II).

3) Molecular weight was measured using a column for liquid chromatograph (ALC / GPC150C) (Shodex 80M / S + 803S + 802S). The column temperature was 135 ° C, trichlorobenzene was used as the solvent, a calibration curve was prepared using 10 TSK standard polystyrenes, and polyethylene was dissolved in trichlorobenzene to measure molecular weight.

4) The amount of static charge was measured by a blow off measuring device.

5) Washing performance: 999 copies of the untransferred black belt having a width of 5 cm were subjected to three consecutive tests by the blade cleaning method.

(Circle): When copying more than 200 sheets, the toner cleaning on the photoreceptor was performed without a problem.

(Triangle | delta): The washing | cleaning performance fell when copying 1,000-1,999 characters.

X: When copying 999 sheets or less, washing performance was reduced.

6) "No abnormality" means no defects (black spots, black lines, blurring, etc.) occur when 100,000 copies are made.

7) "Abnormal" means that no copying or condensation occurs at the 100,000th copy.

8) CaSt (Calcium Stearate) is a metal soap.

As indicated from the results in the above table, when using the dry developer prepared in the embodiments of the present invention, a stable amount of static charge can be obtained and a good phase is formed. In addition, the dry developer of the present invention is excellent in washability and does not cause a problem in storage stability of the toner.

As described above, by adopting the above-mentioned dry developer configuration, a dry developer having remarkably excellent cleaning and environmental stability and durability is obtained, and forming a toner film on the photosensitive member by forming a suitable polyethylene film or layer on the photosensitive member. It can prevent, and can prevent the cleaning failure due to the adhesion of paper dust.

In particular, the above-mentioned effect becomes more remarkable when the high-speed developing treatment for developing the latent images moving at high speed under the manner of using the organic belt photosensitive member and the dispersion-containing developer containing dispersion.

Although the present invention has been described as specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the present invention.

Claims (8)

It is composed of a dispersion carrier composed of toner, resin and magnetic powder, and characterized in that polyethylene having a molecular weight of 10,000 or less, a density of 0.95 or more and an average volume diameter of 15 μm or less is externally blended or directly mixed with the toner. Dry developer for photo processing. The dry developer for electrophotographic processing according to claim 1, wherein the polyethylene content is 0.01 to 10% by weight based on the total weight of the toner. The dry developer for electrophotographic processing according to claim 1, wherein an average particle diameter of the toner is about 30 µm or less. The dry developer for electrophotographic processing according to claim 1, wherein the average particle size of the toner is 3 to 20 m. The dry developer for electrophotographic processing according to claim 1, wherein the carrier has an average particle diameter of about 20 to 400 mu m. The dry developer for electrophotographic treatment according to claim 1, wherein the carrier has an average particle diameter of 30 to 200 mu m. The dry developer for electrophotographic treatment according to claim 1, wherein the polyethylene has an average volume diameter of 10 µm or less. The dry developer for electrophotographic processing according to claim 1, wherein the polyethylene has a molecular weight of 900 µm 10,000, a density of 0.95-0.99 and an average volume diameter of about 3-10 µm.